1. Field of the Invention
The present invention belongs to a field of an optical recording and reproducing apparatus in which recording can be successively continued right after a previously recorded portion when recording is conducted on an optical recording medium.
2. Description of the Related Art
A write-once type optical recording medium is defined as an optical recording medium in which recording can be conducted only once in one area of an optical recording medium on which recording has not been conducted yet. As one of the write-once type optical recording medium, there is provided a successively writing type optical recording medium in which one piece of information is recorded in one area of the optical recording medium at present and then another piece of information can be recorded in another area which is located successively to the above area in which one information has been previously recorded.
Conventionally, as the successively writing type optical recording medium, there is provided a CD-R which is an abbreviation of CD-Recordable. FIGS. 4A to 4C are views showing a recording format (packet) of CD-R. As shown in FIG. 4A, CD-R includes: a first link block for linking a record with a final portion of the previous data; a run-in area in which only data expressing a start position of recording is recorded in 4 sectors; a user data area; a run-out area in which only data expressing an end position of recording is recorded in 2 sectors; and a second link block expressing the next writing position.
In the case where recording is conducted on an optical recording medium having the above structure, when an electric power failure has occurred in the process of recording a piece of information or when an operator mistakenly has turned off an electric power source, recording can not be properly conducted and further recording is stopped. In this case, since the recording and reproducing apparatus is stopped before the completion of normal recording, a recording signal is suddenly stopped in the middle of recording information.
In the above case, since recording is not properly completed, the run-out area and the second link block, which should be written in the case of normal recording, are not written on the optical recording medium. When the second link block is not written on the optical recording medium, it is impossible to determine a starting position of the next time recording, and further there is a possibility that data has been broken in an end block at the previous recording position. For the above reasons, it is impossible to continue to record the following data right after the recording end position of the last time on the optical recording medium.
In the above case, when the next recording is conducted after an error position of the optical recording medium in the optical recording and reproducing apparatus, it is necessary to recover the error before conducting the next time recording and make a link block so that the next time recording can be properly conducted.
In the case of the arrangement of packets of CD-R, when an error occurs in the middle of recording information, the final packet is ended without being composed of the run-out area and the second link block as shown in FIG. 4B. Accordingly, it is possible to judge the occurrence of an error when the run-out area or the second link block is not detected.
When the run-out area or the second link block is not detected, it is judged that a recording error has occurred. Then, a run-in area of the final packet, in which the recording error has occurred on the optical recording medium, is detected in the optical recording and reproducing apparatus.
Next, a period of time from the detected run-in area to a point of time at which RF signal is not detected, or a period of time from a head portion of user data, which follows the detected run-in area, to a point of time at which RF signal is not detected is measured, and a position of data to be repaired is specified by the thus measured time information.
Next, as shown in FIG. 4C, dummy data is written at positions where RF signal is lost and also at hatched positions, and dummy user data, run-out area and link block are recorded, so that data can be repaired. Data can be successively written after the repaired data in the same manner as that of normal operation.
At present, instead of CD-R, an optical recording medium such as DVD-R, which is a successively writing type optical recording medium, is proposed. FIGS. 5A to 5C are views showing an arrangement of recording packets of DVD-R. As shown in FIG. 5A, in the case of DVD-R, a unit of recording is a type of ECC (error correction code) block. A reading unit is also a type of ECC block. In the case of DVD-R, a link flag is put up together with user data in the final sector of final ECC of recorded user data. An overwriting area is provided in the first sector of the next ECC block. When the successively writing operation is conducted, the writing of the next time is linked with the overwriting area.
In the case of DVD-R, an ECC block is used as a unit when signals are read. Therefore, an incomplete ECC block is not recognized as data. Unlike a run-in and a run-out area of CD-R, DVD-R has no sectors in which only a signal of start of recording or a signal of end of recording is written.
Accordingly, in the case of DVD-R, it is impossible to use an error detection method, which is used in the case of CD-R, in which only an area having a special signal such as a run-out signal or a link block is extracted. Therefore, in the case of DVD-R, whether or not the recording is ended is judged by the existence of a link flag in the final sector of ECC block, which has been finally recorded, in ECC blocks which can be detected and perfectly recorded. In the case where the link flag is not put up in the final sector of the final ECC block which can be detected at that time, it is possible to judge that an error of recording has occurred in the next ECC block.
However, according to the above method, the following problems may be encountered. For example, even if a link flag is written in the final sector of the final ECC block which can be detected, when recording is stopped for some reasons before one ECC block is recorded after recording has been started on the ECC block right after that, it is judged that recording is conducted properly because the link flag is put up in the final sector of the final ECC bloc which can be detected. Therefore, with respect to the ECC block arranged right after that, it is impossible to know that an error of recording has occurred.
Accordingly, when the successively writing operation is conducted, there is a possibility that the next recording data is overwritten on the ECC block in which the error has been caused. In this case, it is impossible to conduct overwriting in the same area in the successively writing type optical recording medium. Therefore, the successively writing data is also damaged.
The present invention has been accomplished to solve the above problems. It is an object of the present invention to provide an optical recording and reproducing apparatus in which a successively writing position can be specified quickly and accurately when successive writing is conducted on an optical recording medium composed of only a link block and user data. More particularly, it is an object of the present invention to provide an optical recording and reproducing apparatus in which the final recording position can be specified quickly and accurately in order to recover an error of recording when the error has occurred in the middle of recording in the last time.
According to a first aspect of the present invention, there is provided an optical recording and reproducing apparatus comprising: a pickup for obtaining an information signal from reflected light when light is irradiated to and reflected on an optical recording medium; an RF signal detection means for obtaining an RF signal from a reflected light signal supplied from the pickup; a final recording unit extraction means for extracting a final recording unit, which has been properly recorded, from RF signal, the final recording unit being contained in RF signal; a timer means for measuring a period of time from a head of a data block right after the final recording unit to a point of time at which RF signal is not detected; a last time final recording position specifying means for specifying a last time final recording position; and a recording error judgment means for judging whether or not a recording error occurred last time.
Therefore, even if data, which has been written in a successively writing type optical recording medium, causes a writing error in a data block next to a data block in which the final link flag has been detected, it is possible to positively detect the writing error.
According to a second aspect of the invention, there is provided an optical recording and reproducing apparatus according to the first aspect of the invention, wherein the error judgment means comprising: a recording end information detection means for detecting recording end information existing at a predetermined position in the final recording unit; and a time information judgment means for judging whether or not a value of time information obtained by the timer means is a predetermined value according to the recording end information.
Accordingly, even if information of end of recording is recorded in the final recording unit, it is possible to check a recording error in the next recording unit. Therefore, the successively writing operation can be safely conducted.
According to a third aspect of the invention, there is provided an optical recording and reproducing apparatus according to the first aspect of the invention, further comprising a pseudo data generation means for recording pseudo data for recovering an error in a recording unit including a final recording position and also including a recording unit right after that when a recording error signal is received from the error judgment means.
Accordingly, it is possible to smoothly recover a recording error at a position where the recording error has occurred.
According to a fourth aspect of the invention, there is provided an optical recording and reproducing apparatus according to the first aspect of the invention, wherein the timer means is a pulse signal counter synchronized with a writing block contained in data to be written in.
Accordingly, it is possible to accurately recognize the successively writing position without using a large-scale complicated timer unit.